The Horrocks correspondence for coherent sheaves on projective spaces

Iustin Coanda

Published 2008-11-24, updated 2010-03-23Version 5

We establish an equivalence between the stable category of coherent sheaves (satisfying a mild restriction) on a projective space and the homotopy category of a certain class of minimal complexes of free modules over the exterior algebra Koszul dual to the homogeneous coordinate algebra of the projective space. We also relate these complexes to the Tate resolutions of the respective sheaves. In this way, we extend from vector bundles to coherent sheaves the results of Coand\u{a} and Trautmann [Trans. AMS 385 (2005)], which interpret in terms of the BGG correspondence the results of Trautmann [Math. Ann. 237 (1978)] about the correspondence of Horrocks [Proc. London. Math. Soc. 14 (1964)], [Asterisque 71-72 (1980)]. We also give direct proofs of the BGG correspondences for graded modules and for coherent sheaves and of the theorem of Eisenbud, Floystad and Schreyer [Trans. AMS 355 (2003)] describing the linear part of the Tate resolution associated to a coherent sheaf. Moreover, we provide an explicit description of the quotient of the Tate resolution by its linear strand corresponding to the module of global sections of the various twists of the sheaf.